The middle missions (eg the pirate one) were a little more fleshed out. I got the impression that V was in a hurry to get the campaign done, so on the last mission they said, "Alright, let's keep the briefing/debriefing to a few paragraphs, put Alpha 1 against a Loki wing with 99 respawns, put the Hades for the endgame boss, and call it an epic mission". There was an article on Volition Watch a few weeks before Silent Threat came out; they predicted that ST was meant to be a rushed expansion pack to boost slipping FS1 sales. Kind of like Attack of the Clones. It's worth noting that ST usually came for free with a copy of FS1, that's how cheap it was.
I don't see why you guys are that hard on the campaign, though. Look for the positive points, they were there. I remember the first time I saw the Loki I thought it was the coolest fighter of them all. So high-tech, with that cool tiger-teeth logo. The campaign had some good surprises. But I was about 10 when I first played it, so I guess now that I'm older the memories have worn off and I have to join in the bashing.
And anyone who says the Loki is junk needs to play on Insane. Play Field of Destruction with your wingmen as Ulysses/Herc, and then as Loki. The AI does extremely well in that ship, for some reason, even if human pilots have better choices.
edit: Oh, and some pretty bad stand-alone missions, too. They basically accepted everyone they could within the 2-3 week development period.